AQA GCSE Physics (8463), Higher tier · Particle model of matter › Internal energy and energy transfers
Practise Internal energy. 12 exam-style questions on this subtopic, at up to four difficulty levels, with full mark schemes and a progress tracker. Free, no account needed.
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Heating a system increases the energy of the particles in the system. Give the two possible effects of heating a system.
Its temperature rises, or it changes state.
Complete the sentence. The internal energy of a system is the total ................ energy and ................ energy of all the particles that make up the system.
kinetic; potential
Sample questions
Written for this site in the style of AQA exam questions. They are not taken from real past papers.
Question 1Easy4 marks
(a) Which statement describes the internal energy of a system? Tick (✓) one box.[1]
The total kinetic energy of all the particles in the system
The total kinetic energy and potential energy of all the particles in the system
The total potential energy of all the particles in the system
The average kinetic energy of the particles in the system
(b) Heating a system increases the energy of the particles in the system. Give the two possible effects of heating a system.[2]
(c) A saucepan of water is heated on a cooker. What happens to the internal energy of the water?[1]
Show the answer and mark scheme
(a)Answer: The total kinetic energy and potential energy of all the particles in the system
(b)Answer: Its temperature rises, or it changes state.
the temperature of the system increases
the system changes state (e.g. melts or boils)
(c)Answer: It increases.
it increases
Question 2Medium5 marks
A block of ice at −10 °C was taken out of a freezer and put in a warm room. The ice warmed up to 0 °C and then melted.
(a) Describe what happens to the particles in the ice as its temperature increases from −10 °C to 0 °C.[2]
(b) While the ice is melting, its temperature stays at 0 °C even though energy is still being transferred to it. Explain what happens to the internal energy of the ice while it melts.[3]
Show the answer and mark scheme
(a)Answer: The particles vibrate more vigorously about their fixed positions: their average kinetic energy, and so the internal energy of the ice, increases.
the particles vibrate faster / with a larger amplitude (about their fixed positions)
the (average) kinetic energy of the particles increases
the internal energy of the ice increases
(b)Answer: The internal energy increases. The energy increases the potential energy of the particles as the bonds holding them in place are broken, but their kinetic energy stays the same, so the temperature stays at 0 °C.
the internal energy (of the ice) increases
the (average) kinetic energy of the particles does not change because the temperature is constant
the potential energy of the particles increases (as the forces / bonds holding the particles in place are overcome)
Question 3Hard6 marks
Water boils at 100 °C. While water is boiling, its temperature does not change, even though energy is still being transferred to it.
(a) Compare the internal energy of 1 kg of water at 100 °C with the internal energy of 1 kg of steam at 100 °C. Explain your answer in terms of the energy of the particles.[4]
(b) Burns caused by steam at 100 °C are usually much more serious than burns caused by the same mass of water at 100 °C. Suggest why.[2]
Show the answer and mark scheme
(a)Answer: The steam has more internal energy. Both are at 100 °C, so the particles have the same average kinetic energy, but the particles in the steam have much more potential energy because energy was supplied to pull them apart.
the steam has more internal energy
the (average) kinetic energy of the particles is the same (because the temperature is the same)
the (total) potential energy of the particles in the steam is greater
because energy was transferred to separate the particles / to overcome the forces (bonds) between them
(b)Answer: Steam first condenses on the skin, transferring its large latent heat, and the hot water formed then cools as well, so far more energy is transferred to the skin.
when steam condenses on the skin it transfers a large amount of energy (latent heat) to the skin without its temperature falling
the condensed water then cools as well, so the steam transfers much more energy to the skin than the same mass of water